Today, I cut the window openings and completed the remaining patch needed. Since I'm using the full height of the walls and not setting the floor into the grooves, I filled those gaps with two layers of strip wood.

Since the plywood patches for the gable and window were thinner than the mdf on one of the walls, I added 1/64 veneer to even out the surface.

The new door wall will need to be padded to accommodate the custom door frame I'll build to hold the door and screen door. I'm thinking of making this angled wall removable to have access to the interior beyond just the removable roof.  I still need to cut one more roof piece from plywood since I didn't have enough boards in my stash. I had used the original mdf roof board to cut the new front and door walls to keep the material consistent.

The height of the foundation is already better - makes the horse look more in proportion, though the landscaping will be built up and around the foundation to some extent. I'm planning a tree as well, possibly a stitched rug if I can fit it into the timeline. :] Feeling motivated finally!